Shoutbox

There should be no problem, no matter what id you use. Your problem is usually caused when Messenger can't find the image you put as a background so it cannot show the toast. Are you sure you have the right code in your SkinInfo? Remember that the image should be replaced below the <New> tag

About your other question. If I understood correctly, you want to change the color of the nickname and psm. Then, you just need to open style file 923 and edit their foregrounds.